Patents by Inventor Kazuhiro Yoshizawa

Kazuhiro Yoshizawa has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5140628
    Abstract: In a method and apparatus for controlling a radio telephone system, a speech channel is established between the slave radio set of a plurality of radio telephone sets and a radio set of a base unit. An intercom switch for selecting intercom performances is provided for respective radio telephone sets. The slave radio sets of the radio telephone sets are turned OFF when the intercom switch is OFF, and transmitters of the slave radio sets of the radio telephone sets are turned ON. Consequently the connection between a wired telephone channel and the plurality of radio telephone sets can be controlled with a single base unit connected to the wired telephone channel.
    Type: Grant
    Filed: November 30, 1989
    Date of Patent: August 18, 1992
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Yoshitoshi Murata, Kazuhiro Yoshizawa, Akio Yotsutani, Koichi Ito
  • Patent number: 4897864
    Abstract: A method and apparatus for controlling a radio telephone system wherein a speech channel is established between one radio telephone handset out of a plurality of radio telephone handsets and a base unit. An interphone switch for selecting intercom communication is provided for respective radio telephone handsets. The transmitters of the radio telephone handsets are turned OFF when the intercom switch is OFF, and transmitters of the radio telephone handsets are turned ON when the intercom switch is ON. Consequently the connection between a wired telephone channel and the plurality of radio telephone handsets can be controlled with a single base unit connected to the wired telephone channel.
    Type: Grant
    Filed: April 7, 1988
    Date of Patent: January 30, 1990
    Assignees: Nippon Telegraph and Telephone Corp., NEC Corp., Kabushiki Kaisha Toshiba
    Inventors: Yoshitoshi Murata, Kazuhiro Yoshizawa, Akio Yotsutani, Koichi Ito
  • Patent number: 4802200
    Abstract: A method and apparatus for controlling a radio telephone system of the type wherein a connection between a wired telephone channel and a plurality of radio telephone handsets is controlled by a single base station connected to the wired telephone channel, a ring signal through the wired telephone channel is detected, a paging signal is sent to the radio telephone handsets from the base station when the ring signal is detected and a paging response signal is sent to the base station from the radio telephone handset in response to the paging signal.
    Type: Grant
    Filed: August 26, 1986
    Date of Patent: January 31, 1989
    Assignees: Nippon Telegraph and Telephone Corporation, NEC Corporation
    Inventors: Yoshitoshi Murata, Kazuhiro Yoshizawa, Akio Yotsutani, Koichi Ito
  • Patent number: 4802201
    Abstract: Where a carrier wave is received from a called radio telephone set and where the identification signal of the radio telephone set coincides with a preassigned identification signal, transmission of a paging signal from a base unit is stopped. Even when the identification signals do not coincide with each other, the paging signal is sent continuously over a definite interval. Communication is established only when the signal from a handset to the base station has a predetermined strength and a proper I.D.
    Type: Grant
    Filed: September 29, 1986
    Date of Patent: January 31, 1989
    Assignees: Nippon Telegraph and Telephone Corporation, NEC Corporation, Kabushiki Kaisha Toshiba
    Inventors: Kazuhiro Yoshizawa, Akio Yotsutani, Noboru Saegusa, Koichi Ito, Syozi Huse, Akio Toki
  • Patent number: 4776001
    Abstract: A method and an apparatus are disclosed for controlling a radio telephone system comprising a single master apparatus connected to a subscriber line and a plurality of radio telephone sets connected to the master apparatus by way of radio channel. When a call origination operation is made by one of the radio telephone sets, a call originating signal is sent to the master apparatus from the call originating radio telephone set. In response to the call originating signal, the master apparatus switches its radio channel to an idle speech channel, and sends a channel designating signal representing the idle speech channel to the plurality of radio telephone sets including the call originating radio telephone set so as to switch the radio channels of the radio telephone sets which have received the channel designating signal to the idle speech channel.
    Type: Grant
    Filed: August 26, 1986
    Date of Patent: October 4, 1988
    Assignees: Nippon Telegraph and Telephone Corporation, NEC Corporation, Kabushiki Kaisha Toshiba
    Inventors: Yoshitoshi Murata, Kazuhiro Yoshizawa, Akio Yotsutani, Koichi Ito
  • Patent number: 4736461
    Abstract: A portable unit that may be called from a base station through a radio control channel by a succession of terminating call signals that is sent through the control channel from the base station to the portable unit for a first or restricted time duration (T.sub.1), selected in consideration of a battery saving period of a battery saving operation carried out in the portable unit. Within the battery saving period, the portable unit is put into transient active and inactive states during a first time interval and a second time interval, respectively. Selection is made so that the first time duration is longer than the second time interval to receive at least one of the terminating call signals within the first time duration in the portable unit. The base station monitors an acknowledgement signal for a second time duration (T.sub.2) after the lapse of the first time duration and interrupts the control channel when the acknowledgement signal is not received within the first and the second time durations.
    Type: Grant
    Filed: February 12, 1987
    Date of Patent: April 5, 1988
    Assignees: Nippon Telegraph & Telephone Public Corporation, NEC Corporation, Kabushiki Kaisha Toshiba
    Inventors: Ryoji Kawasaki, Kazuhiro Yoshizawa, Akio Yotsutani, Noboru Saegusa, Koichi Ito, Syozi Huse
  • Patent number: 4726052
    Abstract: In a radio telephone system comprising a radio telephone set utilizing a rechargeable battery, and a base unit connected to the radio telepone set through a radio channel for exchanging a speech signal between the radio telephone set and a wired telephone line, there are provided a detector for detecting the charged state of the battery, a terminating device responsive to the output signal of the detector for terminating the radio channel between the radio telephone set and the base unit.
    Type: Grant
    Filed: October 2, 1986
    Date of Patent: February 16, 1988
    Assignees: Nippon Telegraph & Telephone Corp., NEC Corp., Kabushiki Kaisha Toshiba
    Inventors: Kaoru Kato, Kazuhiro Yoshizawa, Akio Yotsutani, Noboru Saegusa, Isao Sasaki, Koichi Ito, Akio Toki
  • Patent number: 4679244
    Abstract: A portable unit that may be called from a base station through a radio control channel by a succession of terminating call signals that is sent through the control channel from the base station to the portable unit for a first or restricted time duration (T.sub.1), selected in consideration of a battery saving period of a battery saving operation carried out in the portable unit. Within the battery saving period, the portable unit is put into transient active and inactive states during a first time interval and a second time interval, respectively. Selection is made so that the first time duration is longer than the second time interval to receive at least one of the terminating call signals within the first time duration in the portable unit. The base station monitors an acknowledgement signal for a second time duration (T.sub.2) after the lapse of the first time duration and interrupts the control channel when the acknowledgement signal is not received within the first and the second time durations.
    Type: Grant
    Filed: February 26, 1985
    Date of Patent: July 7, 1987
    Assignees: Nippon Telegraph & Telephone Public Corporation, NEC Corporation, Kabushiki Kaisha Toshiba
    Inventors: Ryoji Kawasaki, Kazuhiro Yoshizawa, Akio Yotsutani, Noboru Saegusa, Koichi Ito, Syozi Huse